ipv6 error (no such host) for ipv6.dns1.nextdns.io and ipv6.dns2.nextdns.io

I'm having trouble reaching a few endpoints.

diag output log contain ipv6 error (no such host)

Fetching PoP name for ultra low latency primary IPv6 (ipv6.dns1.nextdns.io)
Fetch error: Get "https://dns.nextdns.io/info": dial tcp: lookup ipv6.dns1.nextdns.io: no such host
Fetching PoP name for ultra low latency secondary IPv6 (ipv6.dns2.nextdns.io)
Fetch error: Get "https://dns.nextdns.io/info": dial tcp: lookup ipv6.dns2.nextdns.io: no such host 

my diag result: https://nextdns.io/diag/292b4580-9157-11f1-8245-a985051d0915

my ping.nextdns.io result: